The present invention relates to a high-pressure fuel pump control device and an in-cylinder injection engine control device, and particularly to a high-pressure fuel pump control device and an in-cylinder injection engine control device for controlling the operation of a high-pressure fuel pump for force-feeding a high pressure fuel to a common rail of a fuel injection valve.
The present vehicle needs to reduce exhaust gas substance such as carbon monoxide (CO), hydrocarbon (HC), nitrogen oxides (Nox), etc. contained in a vehicle exhaust gas from the view point of environment protection. The development of a direct injection engine (in-cylinder injection engine) has been done with the aim of reducing these gas substances. The in-cylinder injection engine directly injects a fuel from a fuel injection valve within a combustion chamber in a cylinder. Further, the fuel injected from the fuel injection valve is reduced in particle diameter to thereby promote or accelerate the combustion of the injected fuel and achieve a reduction in exhaust gas substance and an improvement in engine output, etc.
Reducing the particle diameter of the fuel injected from the fuel injection valve here needs means for bringing the fuel to high pressure. Various technologies for a high-pressure fuel pump for force-feeding a high pressure fuel to the fuel injection valve have been proposed (see, for example, Japanese Patent No. 2690734, Japanese Patent Laid-open No. Hei 10-153157, etc.)
The technology disclosed in Japanese Patent Application No. 2690734 relates to a variable delivery or discharge rate high-pressure pump for force-feeding a high pressure fuel to within a common rail (oil-storage path shared between cylinders) of a fuel injection device. The variable discharge rate high-pressure pump comprises a cylinder, a plunger driven by an engine built in the cylinder a pressure chamber formed by an upper end surface of the plunger and an inner peripheral surface of the cylinder, and an electromagnetic valve which faces the pressure chamber and is fixed to the cylinder. The variable discharge rate high-pressure pump is one in which the electromagnetic valve is energized to thereby close a low pressure path communicating with the pressure chamber, and the fuel placed in the pressure chamber increases in pressure owing to the elevation of the plunger so as to be force-fed to the common rail and hence the electromagnetic valve is opened or closed, whereby the amount of delivery or discharge of the fuel to the common rail is adjusted.
On the other hand, the technology disclosed in Japanese Patent Laid-open No. Hei 10-153157 relates to a variable discharge rate high-pressure pump for adjusting or controlling the amount of a fuel supplied to an engine by a fuel spill valve corresponding to an electromagnetic valve. The variable discharge rate high-pressure pump comprises a cylinder, a plunger built in the cylinder, and a pressure chamber formed by an upper end surface of the plunger and an inner peripheral surface of the cylinder. An inflow path for allowing the fuel to flow from a low pressure feed pump, a supply path for force-feeding a high-pressure fuel to a common rail, and a spill path communicating with a fuel spill valve for returning a fuel spilt from the pressure chamber to a fuel tank are connected to the pressure chamber. The fuel spill valve is opened or closed to thereby control the amount of delivery of the fuel to the common rail.
Meanwhile, the conventional technology disclosed in Japanese Patent Application No. 2690734 has a problem in that the electromagnetic valve which opens or closes the common rail, must be set to an always-opened type to control or suppress the occurrence of a vapor lock due to a substantial reduction in the pressure in the pressure chamber at a suction stroke of the plunger, and when the delivery of a fuel in maximum flow rate from the pressure chamber is made, a loss of a pressure-applying time due to an open delay in the electromagnetic valve occurs when the plunger shifts to a compression stroke, and the capability of fuel delivery is reduced, whereas when the delivery of a fuel in small flow rate from the pressure chamber is made, almost all time necessary for the compression stroke of the plunger is spent in maintaining the electromagnetic valve in an open state, whereby the electromagnetic valve must be opened or closed within a slight time lying between the intake stroke and compression stroke of the plunger.
In the conventional technology disclosed in Japanese Patent Laid-open No. Hei 10-153157, the inflow path and the spill path are provided separately, and the intake stroke of the plunger and the opening and closing of the spill valve are out of relation to the inflow of the fuel. Therefore, the above-described problem is solved. It is however necessary to provide valve sheets at two points with respect to the intake valve for the inflow path and the spill valve for the spill path in addition to a size increase in the variable discharge rate high-pressure pump due to the provision of the spill path. It is also necessary to improve the accuracy of processing of each valve sheet with a view toward preventing a reduction in delivery capability due to leakage of the fuel from the valve sheet. Therefore, the manufacturing cost increases and continuous energization must be carried out while the spill valve is being closed, thus causing inconvenience that power consumption will increase.
Further, any of the respective conventional technologies has a problem in that the operation of the electromagnetic valve must completely be synchronized with the reciprocating stroke of the plunger, and the high response of the electromagnetic valve and the high accuracy of a synchronizing signal are required, whereby a system necessary therefore becomes very expensive.
Here, the present applicant has studied with a view toward solving the above-described problems and proposed the inventions of variable discharge rate high-pressure pumps as the preceding applications in various ways. There is known, for example, a technology of a variable discharge rate high-pressure pump wherein when pressure on the downstream side (pressure chamber side) of an intake valve in an inflow path is equal to that on the upstream side (inflow path side) of the intake valve or greater than that due to a change in the volume of a pressure chamber by a plunger reciprocated according to the rotation of a cam, a push rod is provided in which a valve closing spring urged so as to close the intake valve is provided to close the intake valve and a valve opening spring urged so as to open the intake valve is provided, and the push rod is activated according to the energization or de-energization of a solenoid. Further, the above-described problems are solved owing to the separate provision of the intake valve and the electromagnetic valve, the separate provision of the intake valve and the push rod, and the configuration free of the provision of the valve sheets at the two points, etc.
Meanwhile, an operation timing chart from the start-up of an engine by the variable discharge rate high-pressure pump is shown in FIG. 22. It is understood that the time between the determination of a crank angle signal after the beginning of cranking from the engine start-up and the determination of a plunger phase between the crank angle signal and a cam angle signal for driving a plunger no allows the output of a solenoid control signal, a first solenoid control signal is outputted based on a REF signal only after the plunger phase is established, thereby force-feeding a high pressure fuel to a common rail to start a rise in fuel pressure, and when a second solenoid control signal is outputted to force-feed a fuel to the common rail, a fuel injection valve has fuel pressure 22b. 
Thus, as shown in FIG. 22, even when the plunger shifts to a compression stroke via a bottom dead center from its stop position 22a during the time that elapsed before the determination of the plunger phase, the intake valve cannot be closed. A rise in fuel pressure cannot be achieved during this time, and a time delay up to target fuel pressure is developed. A problem arises in that this causes the lengthening of an engine start-up time and delays the atomizing of an atomized particle size by a fuel injection valve, thus exerting a large influence on the amount of exhaust of HC.
Thus, the present inventors have obtained new findings that it is necessary to control a high-pressure fuel pump in order to allow the force-feeding of a high pressure fuel to the common rail even during the period of from the start of the cranking to the determination of the plunger phase between the crank angle signal and the cam angle signal. However, any of the conventional technologies does not pay particular attention to the planning of the promotion of a rise in fuel pressure from the engine start-up.
The present invention has been made in view of such problems. An object of the present invention is to provide a high-pressure fuel pump control device and an in-cylinder injection engine control device capable of causing a high-pressure fuel pump to promote a rise in fuel pressure from the start-up of an engine, and achieving the shortening of an engine start-up time, a reduction in exhaust gas substance and an increase in engine output, etc.
There is provided a high-pressure fuel pump control device and an in-cylinder injection engine control device according to the present invention, for achieving the above object, which basically includes a fuel injection valve provided in a cylinder, a high-pressure fuel pump for force-feeding a fuel to the fuel injection valve, and a crank angle sensor for detecting the position of a crankshaft of the cylinder. The high-pressure fuel pump includes a plunger for pressurizing the fuel placed in the high-pressure fuel pump, a pump drive cam for driving the plunger, and a cam angle sensor for detecting the position of the pump drive cam. The high-pressure fuel pump control device and in-cylinder injection engine control device include drive signal setting means for outputting drive signals to the high-pressure fuel pump at least two or more times from the time of signal detection of the crank angle sensor to the time of determination of phases of the crank angle sensor and the cam angle sensor.
Further, the high-pressure fuel pump control device and-in-cylinder injection engine control device control an in-cylinder injection engine having a fuel injection valve provided in a cylinder, and a high-pressure fuel pump for force-feeding a fuel to the fuel injection valve. The high-pressure fuel pump includes a plunger for pressurizing the fuel placed in the high-pressure fuel pump, and a pump drive cam for driving the plunger. The high-pressure fuel pump control device and in-cylinder injection engine control device include drive signal setting means for repeatedly outputting drive signals each having a determined width to the high-pressure fuel pump in a predetermined cycle during a period in which the plunger is reciprocated once from the start-up of the in-cylinder injection engine.
The high-pressure fuel pump control device and in-cylinder injection engine control device of the present invention constructed as described above repeatedly output the drive signals each having the predetermined width to the high-pressure fuel pump in the predetermined cycle for a period of from the time of signal detection of the crank angle-sensor for detecting the position of the crankshaft of the cylinder to the time of the determination of the phases of the crank angle sensor and the cam angle sensor for detecting the position of the pump drive cam, i.e., even in a state in which the plunger phase at the engine start-up cannot be detected. Therefore, any of the drive signals is applied in the neighborhood of the bottom dead center of the plunger to promote fuel pressure from the engine start-up, whereby a engine start-up time can be shortened, and a reduction in the amount of exhaust of an exhaust gas substance and an increase in engine output, etc. can be achieved.
Further, the drive signal setting means can also repeatedly output the drive signals each having the predetermined width to the high-pressure fuel pump in the predetermined cycle regardless of the engine start-up. Thus, even when signals outputted from the crank angle sensor and the cam angle sensor fall into a state unable to be absolutely detected due to a break or the like, the fuel can be force-fed to the fuel injection valve, thereby making it possible to achieve failsafe.
According to a specific aspect of a high-pressure fuel pump control device and in-cylinder injection engine control device according to the present invention, the high-pressure fuel pump control device and in-cylinder injection engine control device output each drive signal to the high-pressure fuel pump in synchronism with the rising edge or falling edge of a signal outputted from the crank angle sensor for detecting the position of the crankshaft in the cylinder or in synchronism with the rising edge and the falling edge thereof.
Further, the pump drive cam is characterized in that its position is detected by a signal outputted from a cam angle sensor for detecting the position of a cam shaft of an exhaust valve or intake valve in the cylinder, or that its position is detected by a signal outputted from the cam angle sensor for detecting the position of the crankshaft in the cylinder.
Furthermore, the high-pressure fuel pump control device and in-cylinder injection engine control device include detection signal switching means for performing switching to the signal outputted from the cam angle sensor for detecting the position of the cam shaft of the intake valve in the cylinder or the signal outputted from the crank angle sensor for detecting the position of the crankshaft in the cylinder when the signal of the cam angle sensor for detecting the position of the cam shaft of the exhaust valve in the cylinder cannot be detected. The high-pressure fuel pump control device and in-cylinder injection engine control device also include detection signal switching means for performing switching to the signal outputted from the cam angle sensor for detecting the position of the cam shaft of the exhaust valve in the cylinder or the signal outputted from the crank angle sensor for detecting the position of the crankshaft in the cylinder when the signal of the cam angle sensor for detecting the position of the cam shaft of the intake valve in the cylinder cannot be detected. The high-pressure fuel pump control device and in-cylinder injection engine control device further include another drive signal setting means for repeatedly outputting the drive signals each having the predetermined width to the high-pressure fuel pump in the predetermined cycle when the signal outputted from the crank angle sensor for detecting the position of the crankshaft in the cylinder cannot be detected.
Further, according to another specific aspect of a high-pressure fuel pump control device and in-cylinder injection engine control device according to the present invention, the high-pressure fuel pump control device and in-cylinder injection engine control device include variable valve timing driving means for controlling timing provided to open or close the intake valve or exhaust valve in the cylinder. When the signal outputted from the cam angle sensor for detecting the position of the cam shaft of the intake valve or exhaust valve in the cylinder cannot be detected, the high-pressure fuel pump control device and in-cylinder injection engine control device stop control of open/close timing by the variable valve timing driving means. When the control of the open/close timing by the variable valve timing driving means is discontinued, the high-pressure fuel pump control device and in-cylinder injection engine control device are provided with another drive signal setting means for repeatedly outputting drive signals each having a predetermined width to the high-pressure fuel pump in a predetermined cycle. When the control of the open/close timing by the variable valve timing driving means is resumed, the high-pressure fuel pump control device and in-cylinder injection engine control device return another drive signal setting means to the drive signal setting means.
Furthermore, the high-pressure fuel pump comprises a pump chamber, a solenoid chamber and a cylinder chamber. The pump chamber includes an intake valve provided on the solenoid chamber side and a valve closing spring urged in a direction to close the intake valve. The solenoid chamber includes a solenoid, an intake valve engagement member brought into engagement with the intake valve, and a valve opening spring urged in a direction to open the intake valve.
A high-pressure fuel pump control device and in-cylinder injection engine control device control an in-cylinder injection engine including a fuel injection valve provided in a cylinder, a high-pressure fuel pump for force-feeding a fuel to the fuel injection valve, and a crank angle sensor for detecting the position of a crankshaft in the cylinder. The high-pressure fuel pump includes a plunger for pressurizing the fuel placed in the high-pressure fuel pump, based on a solenoid signal, a pump drive cam for driving the plunger, and a cam angle sensor for detecting the position of the pump drive cam. The high-pressure fuel pump control device and in-cylinder injection engine control device include basic angle computing means for computing a basic angle of the solenoid signal, based on a detected signal outputted from a fuel pressure sensor attached to the fuel injection valve, target fuel pressure calculating means for calculating target pressure, and fuel pressure input processing means for outputting actual fuel pressure, solenoid control signal computing means for computing a reference angle of the solenoid signal, based on these respective means, state transition determining means for determining the state of the in-cylinder injection engine and causing the same to transition, and solenoid driving means for driving a solenoid of the high-pressure fuel pump. The solenoid control signal computing means includes an equal-interval energization control block for giving drive signals to the high-pressure fuel pump at least two or more times from the time of signal detection of the crank angle sensor to the time of determination of the phases of the crank angle sensor and the cam angle sensor, and a feedback control block subsequent to the complete explosion of the in-cylinder injection engine. The respective control blocks are transitioned by the state transition determining means. The high-pressure fuel pump control device and in-cylinder injection engine control device further include solenoid actuation delay correcting means for correcting a delay in actuation of the solenoid, based on the reference angle of the solenoid signal, which is calculated by the solenoid control signal computing means.